Full pair syntax support

[hautajoki]

This pr adds compile-time pair support in add, remove, set, has and get functions. Previously these functions could only be used when both the predicate and the object of the relationship were known. Now we can define the object as a runtime entity id.

interface Fruit {}
interface Likes {}
interface Eats {
	count: number;
}

const alice = spawn();
const bob = spawn();
const charlie = spawn();

const banana = spawn();
add<Fruit>(banana);

add<Pair<Likes>>(alice, bob);
add<Pair<Likes>>(alice, charlie);

add<Pair<Likes, Fruit>>(bob);

set<Pair<Eats>>(bob, banana, { count: 5 });
set<Pair<Eats, Fruit>>(alice, { count: 12 });

for (const [entity] of query().pair<Likes>(alice)) {
	const likedEntity = target<Likes>(entity);
	print(`Entity ${entity} likes ${likedEntity}`);
}

for (const [entity, eatsData] of query<[Pair<Eats, Fruit>]>()) {
	const eatsTarget = target<Eats>(entity);
	print(`Entity ${entity} eats ${eatsData.count} fruit (${eatsTarget})`);
}

// Using Pair<P> to match any target (wildcard), equivalent to Pair<Likes, Wildcard>
for (const [entity] of query<[Pair<Likes>]>()) {
	const likedTarget = target<Likes>(entity);
	print(`Entity ${entity} likes ${likedTarget}`);
}

[Ukendio]

lgtm!